MEMS capacitive cantilever strain sensor, devices, and formation methods

Abstract

An embodiment of the invention provides a MEMS cantilever strain sensor. Capacitor plates in a MEMS device of the invention are carried on cantilevered opposing micro-scale plates separated by a micro-scale gap under an unstrained condition. At least one of the micro-scale plates may be attached to a substrate or forms a substrate, which may be part of a monitored system. When a load is applied to the substrate, distal ends of the opposing cantilevered micro-scale plates become further separated, resulting in a change of capacitance. The change of capacitance is proportional to a load and therefore is an indication of the strain. Electrodes may be integrated into the strain sensor to provide a connection to measurement circuitry, for example. Sensors of the invention also provide for telemetric communication using radio frequency (RF) energy and can be interrogated without a power supply to the sensor.

Description

STATEMENT OF GOVERNMENT INTEREST[0001]This invention was made with government assistance provided by the National Science Foundation under Contract No. BES-0097521. The government has certain rights in this invention.FIELD OF THE INVENTION[0002]A field of the invention is sensing. Another field of the invention is MEMS (micro electro mechanical systems).BACKGROUND OF THE INVENTION[0003]Sensors play an important role in a wide variety of devices as sensors can provide critical information concerning the status, operational conditions, performance, wear, safety, and countless other conditions. Strain sensors provide information about a load. Strain sensing can be useful as feedback in complex control systems, for example, in vehicles, roads, buildings, tools, and electronic systems, as only a few examples. Strain sensors also have a wide variety of applications in the safety systems. Load distributions provide information about the forces within a mechanical structure, including bendi...

AI Technical Summary

Benefits of technology

The invention is a MEMS cantilever strain sensor that uses capacitance to measure strain. The sensor consists of two micro-scale plates separated by a small gap, and when a load is applied to the substrate, the plates become further separated, resulting in a change in capacitance. The sensor can be used without a power supply and can be packaged in a small package. It is highly compact, low power, and can measure strain accurately. The invention also includes fabrication methods for producing the strain sensor.

Problems solved by technology

When a load is applied to the substrate, distal ends of the opposing cantilevered micro-scale plates become further separated, resulting in a change of capacitance.

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